Publications by authors named "Zhelu Hu"

The achievement of both efficiency and stability in perovskite solar cells (PSCs) remains a challenging and actively researched topic. In particular, among different environmental factors, ultraviolet (UV) photons play a pivotal role in contributing to device degradation. In this work, by harvesting simultaneously both the optical and the structural properties of bottom-up-synthesized colloidal carbon quantum dots (CQDs), a cost-effective means is provided to circumvent the UV-induced degradation in PSCs without scarification on their power conversion efficiencies (PCEs).

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Narrow bandgap cubic formamidine perovskite (α-FAPbI) is widely studied for its potential to achieve record‑breaking efficiency. However, its high preparation difficulty caused by lattice instability is criticized. A popular strategy for stabilizing the α-FAPbI lattice is to replace intrinsic FA or I with smaller ions of MA, Cs, Rb, and Br, whereas this generally leads to broadened optical bandgap and phase separation.

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Perovskite solar cells (PSCs) based on the SnO electron transport layer (ETL) have achieved remarkable photovoltaic efficiency. However, the commercial SnO ETLs show various shortcomings. The SnO precursor is prone to agglomeration, resulting in poor morphology with numerous interface defects.

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Recent attempts to improve solar cell performance by increasing their spectral absorption interval incorporate up-converting fluorescent nanocrystals on the structure. These nanocrystals absorb low energy light and emit higher energy photons that can then be captured by the solar cell active layer. However, this process is very inefficient and it needs to be enhanced by different strategies.

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Polypyrrole (PPy) is a conductive polymer and widely applied in different applications owing to its broadband absorption in the UV-visible, near-infrared (NIR), and short-wave-infrared (SWIR) spectrum, excellent conductivity, and strong photothermal effect. In this work, we explored for the first time the photothermal effect of PPy nanoparticles (PPy-NPs) in a photothermal-induced detector structure and developed a new type of air-stable hybrid PPy-NPs/Pt photodetector (PD) with NIR/SWIR sensitivity. By combining PPy-NPs with a platinum (Pt)-resistive pattern, we fabricated PPy-NPs/Pt PDs that are sensitive to illumination in the wavelength range from 800 to 2000 nm.

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Article Synopsis
  • Metal halide perovskites show significant potential for solar energy applications due to their high efficiency and ease of fabrication.
  • Removing excess lead iodide (PbI) from the perovskite layer can improve the performance and stability of solar cells, but the exact impact of this excess is still debated.
  • Treatment with specific organic salts, particularly iodide salts like MAI and FAI, significantly enhances solar cell efficiency and stability compared to samples with excess PbI, maintaining high power conversion efficiency under prolonged illumination.
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The telecommunication wavelength of λ = 1.5 μm has been playing an important role in various fields. In particular, performing photodetection at this wavelength is challenging, demanding more performance stability and lower manufacturing cost.

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Organic-inorganic hybrid perovskite solar cells have attracted much attention due to their high power conversion efficiency (>25%) and low-cost fabrication. Yet, improvements are still needed for more stable and higher-performing solar cells. In this work, a series of TiO nanocolumn photonic structures have been intentionally fabricated on half of the compact TiO-coated fluorine-doped tin oxide substrate by glancing angle deposition with magnetron sputtering, a method particularly suitable for industrial applications due to its high reliability and reduced cost when coating large areas.

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Photodetection in the short-wave infrared (SWIR) wavelength window represents one of the core technologies allowing for many applications. Most current photodetectors suffer from high cost due to the epitaxial growth requirements and the ecological issue due to the use of highly toxic heavy-metal elements. Toward alternative SWIR photodetection strategies, in this work, high-performance heavy-metal-free flexible photodetectors sensitive to λ = 1.

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Short-wave infrared (SWIR) photodetectors, sensitive to the wavelength range between 1 and 3 μm, are essential components for various applications, which constantly demand devices with a lower cost, a higher responsivity and a faster response. In this work, a new hybrid device structure is presented for SWIR photodetection composing a coupling between solution-processed colloidal plasmonic gold (Au) NRs and a morphology-optimized resistive platinum (Pt) microwire. Pt microwires harvest efficiently the photothermal effect of Au NRs and in return generating a change of device resistance.

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Photodetection in the short-wave infrared (SWIR) spectrum is a challenging task achieved often by costly low bandgap compound semiconductors involving highly toxic elements. In this work, an alternative low-cost approach is reported for SWIR sensors that rely on the plasmonic-induced photothermal effect of solution-processed colloidal gold nanorods (Au NRs). A series of uniform solution-processed Au NRs of various aspect ratios are prepared exhibiting a strong and well-defined longitudinal localized surface plasmon resonance (L-LSPR) maximum from 900 nm to 1.

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Thickness-tunable and compact FACsPb(IBr) perovskite thin films are achieved with a large grain size up to 12 microns. They are then employed to fabricate functional solar cells with a simplified planar structure without the use of electron-transport (ETL) layers. These results are highly encouraging for the future large-scale fabrication of FACsPb(IBr)-based solar cells.

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Perovskite solar cells as a hot research topic show the necessity of controlling the interface. In this work, an insulating alkyl chain layer is self-assembled at the perovskite/hole transport material interface, which successfully exhibits a dual function: blocking electron recombination and resisting moisture at the same time. Improved solar energy conversion efficiency and stability of the device are both achieved.

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